Needle thread controlling mechanism



Uct ZO, 1931. c. w. MUELLER 1,827,949

NEEDLE THREAD CONTROLLING MECHANISM Filed July 24, 1930 3 Sheets-Sheet l $5 5 Znmentor,

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(I ttorneg Oct. 20, 1931.

c. w. MUELLER NEEDLE THREAD CONTROLLING MECHANISM 3 Sheets-Sheet 2 Filed July 24, 1930 Gttomeg @Ct. 20, 1931. c, w MU-ELLE'R 1,827,949

NEEDLE THREAD CONTROLLING MECHANISM Filed July 24, 1930 3 Sheets-Sheet 3 Patented Oct. 2 6, 1931 ram-E- I CHARLES w. MUELLER; or sr. nonlsivrissouni, nssienon 'ro LEwIs .inv sinnn s'rrrcn MACHINE German or; snnouis, vrissonni; A CGRPORA'IION or avrAnvE NEE LE THREAD CONTROLLING. MECHANISM I Application filed. any 24,

thread guide, thence downwardly through a spring controller, and back through the guide, and thence downwardly to the needle; It is desirable to have the spring controller of suflicientstrength to resist the dragof' the needlesulficiently and thereby maintain the thread inthe needle groove during the penetrating stroke of the latter. During the" re- I tracting movement of the needle the stitch is being set and the drag of the needle thread is sufficient to flex the controller upwardly. The resistance of this spring controller duringthe setting of each stitch-is such that when sewing extremely thin fabrics the latter become puckered. f 1 Therefore the principal object of'my invention is to provide a controlling device for the needle thread which will be moved positively in a direction towards the stationary 7 guide during the retracting or stitch setting movement of the needleto therebyreduce the resistance of the controller and avoid puckering of the fabrics. I j

Another object of my invention lies in the provision of a cam-actuated lever for positively operating the spring controller in one direction and a spring for returning the lever whereby the controller will remain in its normal or un-moved position duringthe penetrating stroke of-theneedle so as to permit 40 the controller toexert sufficient drag on the thread to maintain said thread in the needle 4roove. 1

With theseand other objects-in view which will more fully appear, the nature of the invention will be more-clearly understood by following the description, the appended claims, and the several views illustrated in the accompanying d i I In the drawings+- I Figure 1 is a front elevation of the stitch- 1930. Serial ndwoam.

ing head and Work presenting mechanism of'a blind stitch sewing machine equipped with my invention, 7 I

;I- Figure 2 is a rear elevationthereof,

i Figure 3 is an elevation partly in section taken on the opposite side of the head from Figure 2, 1

Figure tie a detail elevation partly in section showing the thread controller spring and tl1e-cam-actuated lever therefor, and

on the line '5 5 of Figure 4. I

' Like reference numerals designate corresponding'parts throughout the several figures of the drawlngs. I I I Referring to the drawings, I have shown my invention as applied; to a blind stitch sewing machine of the well known Lewis type wliich in'cludes an overhanging arm '5, a

a stitching head 6, and a work presenting mechanism Fixed to the head 6"is' a sta-', tionary presser foot'8 and cooperating with the presser foot and locatedbelow the same is the work presenting'mechanism 7 which mecha nism cooperates with thenee'dle12 to form a-line of stitches, and as shown this complemental stitch forming mechanism includes a rotaryhook 16 which ismou'nted on "a shaft 1'7, the latter being driven by a; vertical shaft 18 through'the medium of a 2 to 1 coupling 19 from a gear 20 which is driven from the main shaft 15thr0ugh the medium of a l to 1 coupling21.; Thus the hook 16 rotates twice to each'revo'lution of the main shaft 15, or in other words, twice'to veach complete oscillation of'theneedle 12. The

needle thread T which is led from its supply through a stationary disctensiondevice 22 A, which is disposed above the needlelQ, thence 60 Figure 5 is a detailed sectional v ewt'aken below the thread guide'23.

downwardly through a stationary thread guide 23, thence downwardly through a spring controller 24, thence upwardly through the vibratory take-up t, and thence downwardly to the needle 12. The stationary thread guide23 is formed by an opening located in a substantially U-shaped' arm 25 which is rigidly attached to a post 26 which extends laterally from the stitching head,and

is secured to said post by a screw 27 Supported by the post 26 and arranged between the upper and lower'arms of theu-shaped thread guide is the thread controller 24.

' The aboveconstruction is embodied in certain of the Lewis blind stitch machines, and when the needle begins its retracting movement'to set the previously formed stitch the drag of theineedle thread will overcome the inherent inelasticity or tension of the controller 2e and pull said controller upwardly. This has been found to create a puckering to very thin fabrics and I have therefore provided means for overcomingthis objection.

To. this end, I'have provided a cam-actuated lever 28 for positively elevating the ,8. ring controller 241- during the first part of t e retracting movement of the needle so as to reduce the drag on the needle thread-While the previously formed stitch is being set. This lever 28. is fulcrumed intermediate its ends as at 28-01. to the stitching head 6. One end of the lever is disposed directly under and in engagement with the spring controller 24 and the other end of the lever carries a cam roller 29 which engages a cam 30 having diametricallyopposed concentric and eccentric portionsdlgand 32respectively. The lever 28 intermediate itsends is provided with an arm 33(to which: one end of a coil spring 34; is connected, the other .end of: the spring being connectedto the stitching head 6. The spring 34 functions to return thelever 28 to its normal position and also to yieldably ret-ain the roller 29 in engagement with the cam 30. The cam 30 is fixed to a shaft 35 and this shaft is driven through a worm coupling 36 from the vertically disposed hook operating shaft 18. The gear ratio of the coupling36 is such that the cam shaft 35. rotates once to each revolution of the main shaft 15, and consequently the movement of the cam lever 28 is timed with the oscillations of the needle.

In operation assuming the needleto be at the far end of its penetrating stroke and about to be retracted, the spring controller 24; and

' the lever 28 are disposed in their normal positions. At this time the'cam roller 29v is about to ride on the eccentric portion 32 of the cam. Upon rotation of the main shaft 15 the needle will begin its retracting movement to set the previously formed stitch, and

simultaneously therewith the eccentric portion 32 of the cam will oscillate the lever 28 and thereby positively raise or flex the spring controller 24 and'thereby reduce the drag of the needle thread which would otherwise oc-. our, and cause the previously formed stitch to beset without effecting any puokering action to the material being sewed. WVhen the needle is at the other extremeposition of movement and partakes of its forward or penetrating stroke, the concentric'portion 31 of the cam 30 prevents the lever "28 from being moved and consequently the inherent spring in the con+ troller 24:,will place sufficient drag on the needle threadto maintain said thread in the groove of the needle until after the hook has picked up the needle thread loop.

It is of course to be understood that the details of structure and arrangements of parts may be variously changed and modified without departing from the spirit and scope of my invention.

I claim V 1. A needle thread controlling mechanism for blind stitch sewing machines comprising in combination, an oscillatory threaded needle and a complemental stitch, forming mechanism, a stationary needle-thread tension device, a spring needle-thread con troller and guide. between the tension de vice and the needle and normally movablein a direction away from the needle by the needle thread action during retracting movements of the needle, and means for posi-. tively flexing the spring controller towards the tension device during each retracting movement of the needle to reduce the tension on the needle thread during'the setting of the stitches. j

2. A needle thread controlling mechanism for blind stitch sewing machines comprising in combination, an oscillatory threaded needle and a complemental stitch forming mechanism, a stationary needle-thread tension device, a spring needle-thread controller and guide between the. tension device and the needle and normally movable in a direction away from; the needle by the needle thread action during retracting movements of the needle, and means including a cam-operated lever for positively flexing the spring controller towards the tension device during each retracting movement of the needle to reduce the tension on the needle threadduring the setting of the stitches.

a 3. A needle thread controlling mechanism for blind stitch sewing machines comprising in combination, anv oscillatory threaded needle and a complementalstitch forming mechanism, a stationary needleethread tensiondevice, a spring needle-thread controller and guide between the tension device and the needle and normally movable in a direction away from the needle by the needle thread action during retracting movements of the needle, and means 'for positively; flexing the 7 spring. controller towards the tension device dur ng each retracting movementof the needle to reduce the tension on the needle thread during the setting of the stitches, said means comprising a lever having one end located directly under the spring controller and engaging the same, a cam engaging the opposite end of the lever, and a spring for retaining the lever in engagement with the cam.

41:. A needle thread controlling mechanism for blind stitch sewing'machines comprising in combination, an oscillatory threaded needle having a thread groove and a complemental stitch forming mechanism, a stationary needle-thread tension device, a spring needlethread controller and guide between the tension device and the needle and normally movable in a direction away from the needle by the needle thread action during retracting movements of the needle, and means for positively flexing the spring controller towards the tension device during each retracting movement of the needle to reduce the tension on the needle thread during the setting of the stitches, said means comprising a lever having one end located directly under the spring controller and engaging the same, a cam engaging the opposlte end of the lever,

and a spring for retaining the lever in en-' gagement with the cam, the cam permitting the spring controller to return to and remain V in its normal position during the latter part I of the penetrating stroke of the needle tov maintain suflicient drag on the needle thread and thereby retain the latter in the needle groove.

In testimony whereof I afiiX my signature.

CHARLES W. MUELLER. 

